24
ordered in order to ensure that the flanges capping the ends did not heat up during
synthesis.
Figure 2.6 - Continuous pump, xylene∕ferrocene mixture, and mass flow
controllers for vapor-phase CVD.
As the carbon∕catalyst precursors are not gaseous for this method, they need
to be introduced to the system in the liquid state, which necessitates a more
complicated delivery system. Previous methods of liquid delivery include injection
[40], spray [41], and aerosol [42], though these methods all necessitate either a
secondary heater or other hardware to prepare the mixture for introduction to the
reaction zone. For this work, the catalyst∕carbon source mixture used was
ferrocene dissolved in xylene, and with xylene's boiling point being 139 oC, the
mixture must be heated up to this temperature before it can mix with the buffer
gases to pass through the reaction zone.